This invention relates to an apparatus and method for controlling the biasing force exerted by a spring, and has particular application to a device such as a crop conditioner in which a rotatable roller is movably mounted to a frame for movement toward and away from another roller. A spring is employed to bias the movable roller toward the other roller, and the invention is utilized to control the biasing force exerted by the spring.
An implement for mowing and conditioning a crop, such as hay, typically employs a forward cutting assembly for mowing the crop and a pair of rollers between which the mown crop passes. The rollers have irregular mating surfaces which act to crimp the crop passing therethrough, in a process known as conditioning, to quicken drying of the crop.
A spring and chain assembly is employed to urge the rollers toward each other. In the past, a manual mechanical adjustment system has been incorporated into the spring and chain assembly to adjust the biasing force on the rollers. Such a system typically employs a turnbuckle or the like, which can be manually moved to a desired position when the implement is not in operation.
At times during operation of a mower conditioner, a mass of material is encountered which is too large to pass through the rollers. In the past, it has been necessary to cease operation of the implement and to manually remove the mass from in front of and between the rollers, thereafter resuming operation. This is a slow and time-consuming procedure.
The present invention has as its object to eliminate the inconvenience of the above-described procedure and to provide an automatic system for adjusting the biasing force on the rollers. A further object of the invention is to simplify the construction and operation of a mower conditioner, while providing improved operating characteristics.
In accordance with the invention, a mower conditioner or other device has a first roller movably mounted to a frame for movement toward and away from a second roller rotatably mounted to the frame. A mounting system is provided between the ends of the first roller and the frame for allowing movement of the first roller relative to the frame. In a preferred embodiment, the ends of the first roller are rotatably supported by a mounting plate, which is pivotably mounted to the frame. An adjustment subassembly is interconnected between the mounting plates.
The adjustment subassembly preferably comprises a spring having one end connected to one of the mounting plates through a suitable connection system. In addition, the adjustment subassembly includes a base having an extendable and retractable member mounted thereto, with the extendable and retractable member being mounted to the other end of the spring. The base is connected to the other mounting plate through a suitable connection system. In a preferred embodiment, the base comprises a fluid-operated cylinder, and the extendable and retractable member comprises a piston having a rod connected thereto, with the end of the rod being secured to an end of the spring. The cylinder is selectively connectable to a source of fluid pressure and to a reservoir. When fluid pressure is supplied to the cylinder, the rod is retracted so as to extend the spring. When this occurs, the biasing force exerted by the spring on the mounting plates through the connection system urges the first roller toward the second roller. When the cylinder is connected to reservoir fluid and pressure in the cylinder is relieved, the biasing force of the spring causes the cylinder rod to extend, thus relieving the biasing force exerted on the mounting plates. When this occurs, the rollers are operated to move the mass of material therethrough by allowing movement of the first roller away from the second roller.
While the aspect of the invention set forth immediately above has been and will be described in the context of a mower conditioner having a movable roller, it is to be appreciated that this aspect of the invention may also be satisfactorily employed in any other application in which a spring or other biasing member is utilized to exert a biasing force, and adjustment of the biasing force exerted by the spring is desired.
In accordance with another aspect of the invention, a lifting and lowering system is employed for moving the frame of the mower conditioner between an upper inoperative position and a lower operative position. The adjustment subassembly is interconnected with the lifting and lowering system. In a preferred embodiment, the lifting and lowering system includes a fluid operated cylinder having an extendable and retractable rod, and the adjustment subassembly similarly includes a fluid-operated cylinder, as described previously. A control valve provides communication to a source of hydraulic fluid pressure and to a reservoir. The control valve is movable between a first position and a second position. In the first position, the control valve is positioned to expose the lifting and lowering cylinder to reservoir, allowing retraction of its rod and movement of the mower conditioner frame to its lower position. Simultaneously, the control valve provides pressurized fluid to the adjustment cylinder, for retracting its rod and increasing the biasing force exerted by the spring to exert a maximum force urging the movable roller toward the other roller. When the valve is in its second position, fluid pressure is supplied to the lifting and lowering cylinder for raising the mower conditioner frame to its upper inoperative position. Simultaneously, the adjustment cylinder is exposed to reservoir for allowing extension of its rod and relieving the biasing force exerted by the spring. Accordingly, a mass of material can then be to passed through the rollers when the mower conditioner frame is raised.